If you change your availability and find that you are not receiving the training you expect, it may be because the training plan generator has determined that it is better to skip a training session today in favor of a session with more availability in the coming days.
These rules are designed to optimize the training plan based on your availability. For example, if a training session today would prevent a session tomorrow (because it would be too many consecutive days) and tomorrow has more time available, the plan may skip today's session in order to train tomorrow instead. Similarly, if there was a session yesterday and the next two days have more availability than today, the plan may skip today's session in favor of training on the next two days.
Keep in mind that if you go out for a ride regardless of what the training plan says, you may receive a recommendation to skip today's session every time.